Welding of transparent materials using femtosecond laser pulses

We report on laser welding between transparent materials without the insertion of intermediate layers such as glue by use of near-infrared femtosecond laser pulses. When femtosecond laser pulses are focused at the interface of transparent materials, the material around the focal point is melted and resolidified because of the temperature increases due to the localized nonlinear absorption of optical pulse energy. We experimentally succeeded in laser welding between two pieces of silica glass without the insertion of an intermediate layer by femtosecond laser pulses. This technique has a possible application to the joining of semiconductors such as silicon crystals.